The age of the system. Typically, the older a furnace is, the more expensive the repair. That's because older furnaces could have multiple components that are worn out. Nov 19, 2020
Typically, there's a 10 to 15 minutes allowance for this. However, if after this time it's still producing cold air, then there's an underlying problem that needs to be addressed. It would be wise to turn the furnace off and get in touch with a pro immediately for help dealing with the issue. Dec 15, 2021
A clogged air filter restricts airflow through the furnace. This leads to overheating and can cause the system to shut off because the safety switch shuts the unit down when high temperatures are reached. Check the filter and replace it if it's covered in debris.